Secondly, the effect of the addition of precursors on the synthesis of oil from S。 limacinum SR21 was investigated。 When citric acid was added, there was a significant change in oil and DHA, while the biomass did not。 When its concentration was 3 g/L, the content of oil was 0。39±0。01 g/g and DHA content was 0。44±0。01 g/g, which was improved by 21。88% and 25。71% compared with the control group。 When chrysalis oil is added, there was a significant change in DHA, while the biomass and oil did not。 When it was 80g/L, DHA content was 0。43±0。02 g/g, which was increased by 21。88 % compared with the control。 When Twain -80 is added, there was a significant change in DHA, while the biomass and oil did not。 When it was 0。6 g/L, DHA content was 0。48±0。01 g/g, which was increased by 37。14% compared with the control。

Thirdly, enzyme activity analysis was carried out on the key enzymes in the metabolic pathway of oil producing microbial oils。When the time was 72, 56, 46 h, malic enzyme fatty acid synthetase and ATP-citrate lyase activity respectively were obtained the maximum value of 0。76, 2。90 and 1。69 U/mg after adding citric acid。 When the time was 64, 56, 56 h, ME, FAS and ACL activity respectively were obtained the maximum value of 0。344, 2。42 and 1。57 U/mg after adding chrysalis oil。 When the time was 32, 40, 48 h, ME, FAS and ACL activity respectively were obtained the maximum value of 0。36, 0。58 and 1。89 U/mg after adding twain-80, which indicates that FAS and ACL were the limiting enzymes during the process of accumulation of lipids。 The change of ME activity was not the same trend as the process of oil accumulation, ME was also a key enzyme in the process of accumulation of oil。

Finally, the feasibility analysis of the production of DHA was carried out using the fermentation filtrate of the producing yeast。 Considering the economy and efficiency, the optimal condition is that the ratio of wastewater to distilled water is 2:1, the concentration of glycerol in the initial medium is 80 g/L and the hydrolysate is 10 g/L。 At this time, DHA content separately were 0。37±0。01 g/g, which was increased by 18。75 % compared with the control。

Keywords: defatted silkworm pupae; oleaginous microorganisms; precursor; enzyme activity; DHA

目录

第一章 绪论 1

1。1 蚕蛹的综合利用 1

1。1。1蚕蛹的成分 1

1。1。2 蚕蛹的应用 1

1。1。3蚕蛹综合利用的前景 2

1。2 产油微生物 3

1。2。1 产油微生物的种类及应用 3

1。2。2产油微生物的培养条件 5

1。2。3 产油微生物合成油脂的影响因素 5

1。3 微生物油脂的生物合成 6

1。3。1 微生物油脂的简介 6

1。3。2微生物油脂的提取 7

1。3。3微生物油脂的合成途径 8

1。3。4 微生物油脂合成代谢调控 8

1。4本课题研究意义及内容 9

1。4。1 研究意义 9

1。4。2 研究内容 9

1。4。3 技术路线 10

第二章 实验材料和方法 11

2。1 实验材料和仪器 11

2。1。1 菌种